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(11) | EP 0 718 403 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Process for producing human matrilysin by means of recombinant DNA |
| (57) The present invention relates to a process for producing a human matrilysin characterized
in that a human promatrilysin is expressed in E. coli and secreted into the periplasm thereof; the inclusion body is formed, the human
promatrilysin is solubilized with a urea solution, purified and renatured to obtain
the active enzyme (active-type matrilysin). By this process, the active human matrilysin
can be easily produced from transformed E. coli. |
DETAILED DESCRIPTION OF THE INVENTION:
Field of the Invention
[0001] The present invention relates to a process for producing a human promatrilysin (29k) having a molecular weight of 29,000 and a human mature (activated) matrilysin (19k) having a molecular weight of 19,000. More specifically, the present invention relates to a process for producing matrilysin, which comprises designing a nucleotide sequence of a gene such that the enzyme (matrilysin) is efficiently expressed in a microorganism such as E. coli and secreted, artificially synthesizing such a gene, introducing the gene into the microorganism, separating the matrilysin from the cells, and purifying the resulting matrilysin.
[0002] The matrilysin which is obtained in the present invention is useful as a reagent for iatrochemical, biochemical and pharmaceutical investigations, and also useful as a reagent for dispersion of cells to peel off cultured cells of animals from a wall of an instrument or to separate specific cells from tissues of animals. It is particularly useful for dispersing human tissues or cells while maintaining a differentiation activity.
Prior Art
[0003] An extracellular matrix (ECM) is made of a fibrous structural protein, proteoglycan and the like, and it is indispensable for maintaining and forming tissue. As the main structural protein of ECM, collagen, fibronectin and laminin are known. Cancer cells secrete various proteases such as metalloprotease, serine protease, thiol protease and aspartic protease. Of these, metalloprotease is deemed to participate in hydrolysis of the ECM protein and to be associated with metastasis of cancer cells.
[0004] The gene of matrilysin has been also called "pump-1", this name being derived from a putative metalloprotease. This enzyme was firstly purified from postpartum rat uterus [Woessner J. F., Jr., and Taplin, C. J. (1988), J. Biol. Chem., 263, 16918-16925] and a human rectal carcinoma cell [Miyazaki, K., Hattori, Y., Umenishi, F., Yasumitsu, H., Umeda, M. (1990), Cancer Res. 50, 7758-7764]. Quantin et al. expressed pump-1 cDNA in COS cells [Quantin, B., Murphy, G., and Breathnach, R. (1989), Biochemistry 28, 5327-5334]. Ye, Q., -Z. et al. Highly expressed pump-1 in E. coli [Ye, Q, -Z., Johnson, L. L. and Baragi, V (1992) Biochem. Biophys. Res. Commun. 186, 143-149]. However, in this method an inclusion body was formed and the active enzyme could not be obtained.
Problems to be Solved by the Invention
[0005] The abovementioned known methods can be hardly said to be industrially satisfactory in the following points. That is, when animal cells are used as a material in producing both the natural and recombinant-type enzymes (The wording "recombinant-type" means hereinafter "produced by means of recombinant DNA".), a costly culture medium is required for culturing the cells, incurring a high production cost. When the recombinant-type enzyme is highly expressed using E. coli, the insoluble inclusion body is formed, and the active enzyme cannot be obtained.
Brief Description of the Drawings
[0006] Fig. 1 is a view showing the nucleotide sequence and the amino acid sequence of a recombinant-type human matrilysin.
[0008] Fig. 3 is a view showing the constructing of the expression plasmid in the present invention.
Means for Solving the Problems
[0009] In order to solve the abovementioned problems, the present inventors have conducted investigations, and have consequently found a process in which an active human matrilysin is efficiently expressed in E. coli.
This finding has led to the completion of the present invention.
[0010] The process for producing the human matrilysin in the present invention will be described below. The sequence of the human matrilysin gene is already known [Müller, D., Quantin, B., Gesnel, M.C., Millon-Collard, R., Abecassis, J. and Breathnach, R. (1988) Biochem. J. 253, 187-192].
[0011] However, even if the human gene is expressed in Escherichia coli (E. coli), the expression efficiency is generally low, and it is quite difficult to produce the gene product at an industrial level.
[0012] Therefore, in order to efficiently express the human matrilysin gene in E. coli, the nucleotide sequence of the human matrilysin gene has been designed using optimum codons of E. coli. At that time, it has been presumed that when the mature enzyme is directly expressed, the inclusion body is formed without taking the correct stereostructure. Accordingly, the sequence to express promatrilysin has been employed. Further, to express and secrete matrilysin in E. coli efficiently, a signal peptide of E. coli alkaline phosphatase has been added to the N-terminal side. It has been designed that the proenzyme formed in the cells is accumulated in the periplasmic region by cleaving the signal peptide with a signal peptidase.
[0013] The present inventors have succeeded in actually producing the synthetic gene having the sequence of the human matrilysin gene according to such a design. Further, they have confirmed the selection of the expression vector, the production of a recombinant plasmid in which the synthetic gene is inserted into the expression vector, the formation of a transformant by introducing the recombinant plasmid into a host, the cultivation of the transformant, and the expression of the gene. Still further, they have conducted investigations with respect to the procurement of the active enzyme by solubilization and renaturation of the human matrilysin inclusion body, and have succeeded in it.
[0014] The present invention has actually succeeded in expressing the synthetic gene which was so far difficult to be expressed by the gene recombination technique, and has further succeeded for the first time in the production of the active (mature) human matrilysin which could not be obtained so far, by a biochemical method.
[0015] The present invention will be illustrated more specifically by referring to the following Example.
Example 1
(1) Designing of a human matrilysin gene
[0016] In order to efficiently express a human matrilysin gene in E. coli, the sequence of the human matrilysin gene was designed using optimum codons of E. coli. That is, it was not intended to directly express 19k-matrilysin (active type), but a signal peptide of E. coli alkaline phosphatase was added to the N-terminal side in order to efficiently express and secrete 29k-promatrilysin (inactive type). For inserting the gene into an expression vector, a recognition sequence of EcoRI was introduced at the N-terminal side and a recognition sequence of BamHI at the C-terminal side, respectively.
Recognition sequences of PstI, HindIII, KpnI, SmaI and SphI were introduced into the coding region as restriction enzyme cleavage sites for subcloning which were required to analyze the nucleotide sequence of the synthetic gene.
[0017] The nucleotide sequence of the human matrilysin gene is, along with the amino acid sequence thereof, represented in Tables 1 (information) and 2 (formula). In the Sequence listing given hereinafter SEQ. ID. No. 1 is concerned with the DNA fragment encoding the protein and SEQ. ID. No. 2 is specifically concerned with said protein.
Table 1
| - Information - |
| Length of sequence: 825 |
| Type of sequence: nucleic acid |
| Type of strand: double strand |
| Topology: linear |
| Type of sequence : synthetic DNA |
| Origin: |
| Name of organism: human being |
| Characteristics of sequence: |
| Symbol indicating characteristics: CDS |
| Location: 6 . . 818 |
| Method of determining characteristics: S |
| Symbol indicating characteristics: sig peptide |
| Location: 6 . . 68 |
| Method of determining characteristics: S |
(2) Construction of a plasmid for expressing a human matrilysin in E. coli
[0018] The whole DNA of the human matrilysin gene containing the gene of the signal peptide of E. coli alkaline phosphatase was separated into 28 fragments each having a length of approximately 50 bases as shown in Figs. 1 and 2. Each of these was synthesized by a DNA automatic synthesizer. The DNA fragments were ligated with a T4DNA ligase according to the order shown in Fig. 3 to prepare an artificially synthetic gene.
[0019] pλPR having λPR promotor and EcoRI, NcoI, BamHI, HindIII and PstI sites as cloning sites was used as an expression vector. This expression vector was cleaved with EcoRI and BamHI, and the synthetic gene of the human matrilysin was inserted thereinto to prepare pλPR-MAT. The ligation reaction was conducted at 14°C for 16 hours using T4DNA ligase. E. coli N99cI+ (F-, strA, galK2λ-, IN (rrnD-rrnE)1) was transformed by using the reaction product. The thus-obtained plasmid of the transformant strain was separated by an alkali-SDS method, and the insertion of the intended gene was confirmed by analysis with the restriction enzymes. Subsequently, the transformation of E. coli N4830-1 [F-suohis-, ilv-, galK-, (chlD-pgl), (λ, Bam, N+, c1857, H1)] was conducted again.
(3) Culturing of the transformant strain
[0020] E. coli N4830-1 transformed by using plasmid pλPR-MAT was named Escherichia coli N4830-1/pλPR-MAT, and it has been deposited at the National Institute of Bioscience and Human Technology of the Agency of Industrial Science and Technology under FERM BP-4794. This transformant strain was cultured in LB medium containing 50 µg/ml of ampicillin at 30°C for 16 hours. The thus-obtained strain solution was inoculated in an amount of 3% into LB medium containing 50 µg/ml of ampicillin, and cultured at 30°C for 6 hours, and then at 34°C or 42°C for from 1 to 4 hours.
(4) Purification of matrilysin and properties thereof
[0021] When the expression of matrilysin was induced at 34°C, a relatively small amount of 29k-promatrilysin was expressed in the soluble state. When the expression was induced at 42°C, a large amount of 31k-prepromatrilysin containing the signal peptide was expressed in the insoluble state. With respect to 31k-prepromatrilysin, the purification and renaturation were conducted by the following method to obtain the active enzyme.
[0022] The cells (cell pellet) were suspended in 50 mM Tris-HCl buffer (pH 7.5) containing 150 mM NaCl and 0.5 mM EDTA in a volume which was three times that of the cell pellet, and disrupted by a Dyno-Mill. The thusdisrupted cells were centrifuged at 4°C for 20 minutes at 15,000 rpm, and separated into supernatant and precipitate (when the soluble 29k-promatrilysin was expressed, it was purified from this supernatant). The inclusion body was prepared from the obtained precipitate by the following treatment. First, the precipitate was suspended in a 1 M sucrose solution, and the suspension was centrifuged at 10,000 rpm for 15 minutes to obtain the precipitate. The precipitate was suspended in a solution containing 2% Triton X-100 and 10 mM EDTA, and the suspension was stirred at 4°C for 18 hours. This suspension was centrifuged at 10,000 rpm for 15 hours to obtain precipitate. The thus-obtained precipitate was washed with a 10 mM EDTA solution three times to obtain the inclusion body. The thus-obtained inclusion body was dissolved in 10 mM Tris-HCl buffer (pH 7.5) containing 8 M urea and 0.01% Brij35 (buffer A), and applied to an SP-Sepharose column equilibrated with buffer A. The intended protein was adsorbed on the SP-Sepharose column under such conditions. After the column was fully washed with buffer A, the protein was eluted with a linear concentration gradient of NaCl from 0 M to 0.5 M. The intended protein fraction was concentrated with a Diaflow-YM-10 membrane. The concentrated sample was subjected to molecular sieve chromatography using a Superdex 200 column equilibrated with buffer A. By this procedure, 31k-prepromatrilysin containing the signal peptide was purified.
[0023] The fraction containing the 31k-prepromatrilysin obtained by the molecular sieve chromatography was collected, and dialyzed against 50 mM Tris-HCl buffer (pH 7.5) containing 0.5 M NaCl, 0.01% Brij 35 and 1 mM EDTA at 4°C for 17 hours. Then, the 31k-prepromatrilysin was renatured in the soluble state.
[0024] When the thus-obtained 31k-prepromatrilysin was incubated in the presence of 0.1 mM ZnCl2 and 10 mM CaCl2 at 37°C, this 31k-prepromatrilysin was converted into 29k-promatrilysin in an approximate 1 hour, and into 19k-matrilysin in approximate 17 hours.
Effects of the Invention
1. A process for producing a human matrilysin, which comprises efficiently expressing
a human matrilysin gene in a microorganism, separating the human matrilysin from the
cells or culture solution of the microorganism, and purifying the resulting human
matrilysin.
2. The process of claim 1 wherein the microorganism to be cultured is E. coli.
3. The process of claim 1 wherein the matrilysin to be expressed is promatrilysin which
is precursor, and the active matrilysin is obtained by an auto-processing mechanism.
4. The process of claim 1 wherein the amino acid sequence of the matrilysin has a sequence
of E. coli signal peptide at the N-terminal side, and the matrilysin is secreted into periplasm
thereof.
5. The process of claim 4 wherein the signal peptide is that of E. coli alkaline phosphatase.
6. The process of any one of claims 1 to 5 wherein the human matrilvsin gene has the
nucleotide sequence represented by SEQ. ID. No. 1 in the Sequence Listing.
7. A nucleotide sequence containing a human matrilysin gene having the nucleotide sequence
represented by SEQ. ID. No. 1 in the Sequence Listing.
8. A recombinant vector having the nucleotide sequence of claim 7.
9. The recombinant vector of claim 8 which is recombinant plasmid pλPR-MAT having the
nucleotide sequence containing the human matrilysin gene.
10. The process of any one of claims 1 to 6 wherein the microorganism to be cultured is
a transformant in which the vector of claim 8 or 9 has been introduced.
11. A biologically pure culture of Escherichia coli N4830-1/pλPR-MAT, FERM BP-4794.